File - Mrs. Roeders Class

Chapter 5

The Cardiovascular System

Functions of the Cardiovascular System ▪ Consists of the heart, blood vessels and blood ▪ Pumps blood to all body tissues

▪ Blood… ▪ Fluid tissue that transports oxygen and nutrients to body tissues ▪ Returns some waste products from these tissues to the kidneys and carries carbon dioxide back to the lungs ▪ Blood cells are also important to the immune system

THE HEART ▪ Hollow muscular organ ▪ In the thoracic cavity between lungs ▪ Pumps blood through the entire body ▪ The lower tip is called the apex

The Pericardium ▪Double-walled membranous sac that encloses the heart ▪Peri- surrounding, cardi heart, -um singular noun ending

Walls of the Heart ▪ Epicardium – external layer of the heart, and inner layer of the pericardium ▪ Myocardium – Middle (thickest) layer of the heart

▪ Made of Cardiac muscle ▪ Receives oxygen-rich blood from the coronary arteries

▪ Endocardium – Inner lining of the heart

▪ Surface that comes into contact with the blood

Heart Chambers ▪ Atria:

▪ 2 upper chambers ▪ All blood entering the heart comes through an atria

▪ Ventricles

▪ 2 lower chambers ▪ Thicker walls ▪ Pump blood out of the heart

Valves of the Heart ▪ Tricuspid: R atrium and R ventricle ▪ Pulmonary semilunar valve: R ventricle and pulmonary artery ▪ Mitral valve: L atrium and L ventricle (AKA bicuspid) ▪ Aortic semilunar valve: L ventricle and aorta

Systemic and Pulmonary Circulation ▪ Systemic circulation: flow of blood to all parts of the body except the lungs ▪ Pulmonary circulation: flow of blood only between heart and lungs

Blood Flow Through The Heart ▪ Oxygen poor blood enters heart at the RA via the superior and inferior vena cava ▪ Out of the RA thru the tricuspid to the RV ▪ Pumped through the pulmonary semilunar valve and into the pulmonary artery to the lungs ▪ Oxygen rich blood returns to heart via the pulmonary veins and flows into the LA ▪ Thru the mitral valve to the LV

▪ Thru the aortic semilunar valve and into the aorta. ▪ Goes to body, oxygen used up ▪ Starts over again!

The Heartbeat ▪ Rate and regularity of the heartbeat is determined by electrical impulses ▪ Sinoatrial Node (SA node) ▪ ▪ ▪ ▪

Back of RA Establishes rate/rhythm Called the natural pacemaker of the heart This impulse travels over both atria so they contract together

▪ Atrioventricular Node (AV node) ▪ Located on floor of RA ▪ Receives impulse from SA node ▪ Sends impulse to the Bundle of His

▪ Bundle of His ▪ Group of fibers located between the ventricles ▪ Sends impulse to RV and LV and Perkenje fibers

▪ Perkenje Fibers ▪ Located in walls of ventricles ▪ Send impulses thru ventricles so they contract together

Electrocardiogram ▪ P wave – contraction of the atria ▪ QRS complex – Contraction of the ventricles (the atria are relaxing) ▪ T wave – relaxation and recovery of the ventricles

Arrhythmia: loss of the normal rhythm of the heart

asystole

Arteries ▪ Large blood vessels that carry blood away from the heart ▪ Arterial blood is bright red b/c it is oxygen rich ▪ Aorta is the largest blood vessel in the body ▪ Carotid arteries carry blood to head ▪ Arterioles are smaller branches of the arteries that give blood to the capillaries

Capillaries ▪ Smallest blood vessels, only 1 cell thick! ▪ Exchange of oxygen, nutrients and waste materials occurs here ▪ Connect to venules to begin the trip back to the heart

Veins ▪ Return oxygen-poor blood to the heart ▪ Have valves that keep the blood flowing only toward the heart ▪ Two largest veins are the superior vena cava (blood from upper part of the body) and the inferior vena cava (blood from lower part of the body)

Pulse and Blood Pressure ▪ Pulse: rhythmic pressure against the walls of an artery caused by the contraction of the heart ▪ Blood pressure: measurement of the amount of pressure exerted against the walls of the arteries ▪ Systolic pressure – occurs when ventricles contract – it is the highest pressure against the walls of an artery ▪ Diastolic pressure – occurs when ventricles are relaxed

Blood the “Fluid Tissue” ▪ Plasma

▪ Straw-colored fluid (91% water); contains nutrients, hormones and waste products

▪ Erythrocytes

▪ Mature red blood cells, made in red bone marrow, transports oxygen using the protein hemoglobin

▪ Leukocytes

▪ White blood cells, defend the body ▪ Most common is the neutrophil

▪ Thrombocytes

▪ AKA platelets, small, important in clotting

Blood Types ▪Classified according to the presence or absence of certain antigens (something the body sees as foreign) ▪A, AB, B, O The universal red cell donor has Type O negative blood type. The universal plasma donor has Type AB positive blood type.

Terms related to blood ▪ Hematologist: physician who specializes in diagnosing and treating abnormalities, diseases and disorders of the blood and blood forming tissues ▪ Hemostasis: To stop or control bleeding ▪ Forming a blood clot ▪ External pressure to block blood flow